MURIDZ—DIFFERENTIAL CHARACTERS. 
Diagnostic table of some cranial and dental characters of North American Murrb2—Continued. 
MURID&. 
MURINE. | ARVICOLINZE. 
Mures. Sigmodontes. 
Hespero- | 
mys. Arvicola, 
| Neotoma. 
Sigmodon. 
Ochetodon. 
Vesperimus. 
Oryzomys. 
Myonomes. 
Chilotus. 
Pitymys. 
Evotomys. 
Synaptomys. 
Myodes. 
| Cuniculas. 
Mus. 
Onychomys. 
| Pedomys. 
Fiber. 
Palate (on the whole): 
Little ascending anteriorly—nearly plane. -...--. + + a | ales ee 
Sinuate, low behind, bigh-arched in front .......-| ------ wall leet Pare fre ||hreaill) mea ||to leeds Fait ea fle F oy ita es 
Incisive foramina: 
Long, reachmg opposite molars .....-.---.------ ae ein ar|lar | arpa || if oo on elle 
Short, not reaching opposite molars ...----.-----| ------ cols lca || ce ee |lan |] Se Wise |) te jtah |} ae | te) oe 
Interorbital constriction : 
Warrower than)rostrum) 2-2-2 2-20... -.cs-scene aS 
About equal in breadth to rostrum =| Ss 
Rather broader than rostrum, or much broader..| + +{+}]+)+]/+]4+ 
Margin of orbit posteriorly: 
With a sharp edge, or even raised bead ..--..--- + Se Pi Pcs oa all sll Ut al 
Smooth and rounded off, or with intraorbital ridge] ------ | -- | -- | --|--]--}--|]+])+/+])]4+4]4]4]4 
Palate ending posteriorly : - 
As a broad, transverse, straight shelf across 
space between second and third molars.--..--. 
Similar shelf, but not quite so perfectly trans- 
verse, and with lateral fossw shoved under its 
ponder seceescan HERDOU SaUSCO GE SooeearBaSlesee 
Similar shelf, but still less excavated at sides, | 
and without lateral fcssm@ ..........--..--.---- eeeeacy| | -dullfee [Reel texal eles hes 
Similar shelf, but about opposite Jast molar, the 
shelf narrow, occupying only the median part, 
and without lateral fossw .....--.--..--------- 
As in the last, but farther back, and with a 
small fossa on each side ....-...--------------- 
As in the last in shape, but in position far back 
of the molars, and without fosse 
With a median emargination, opposite the sec- 
ond and third molars, bounded on each side by 
a deep fossa; this terminal portion of the pal- 
ate on a different plane from the rest..........| ------ AEE oe || cecal Pees [cea | fier (eS) tS LS |S 
Upper incisors : 
Smooth : + Jti]+]--} +/+) 4+] 4+) 4)4)4+]4]- 
Grooved 
Each wider across than deep atl cos tes 6 - 
No wider than, or narrower than, deep.......... + Sal Vi ll llc ic a [ic |e esl eee easel eee Jase! ees 
Under incisors: 
Ranning up back of condylar process............ + +/+i4+/4+/4+)4+) 4+) 4+/4+/4/+4+ 
Stopping abruptly at posterior molars........--.| .....- Soil | foo| hea |! feed fees |} ee [rool eer Rect! Sal Se 
ae 
au 
AF 
a 
at 
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ave 
++ 
Molars : 
Rooted: 
With 2'rootsapiece ......-..2-2..--....- 
First upper one with 2 or 3 roots........ 
We om oe te 253) OTM A;TOOTS. «<== 
3,4,or more roots.; + 
“ “ “ “ 
